Re: [PATCH v3 28/33] drm/vkms: Introduce configfs for connector EDID

José Expósito
2025-12-29T17:24:14Z

On Mon, Dec 22, 2025 at 11:11:30AM +0100, Louis Chauvet wrote:
> Introduce new attributes to configure EDID of a connector:
> - edid_enable - chose if the connector will have an EDID or not
> - edid - raw edid content
>
> Due to limitation of ConfigFS, the max len of EDID is PAGE_SIZE (4kB on
> x86), it should be sufficient for many tests. One possible evolution is
> using a ConfigFS blob to allow bigger EDID.
>
> Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
> Signed-off-by: Louis Chauvet <louis.chauvet@bootlin.com>
> ---
> Documentation/ABI/testing/configfs-vkms | 14 ++++++
> Documentation/gpu/vkms.rst | 5 ++-
> drivers/gpu/drm/vkms/vkms_configfs.c | 80 +++++++++++++++++++++++++++++++++
> drivers/gpu/drm/vkms/vkms_connector.c | 3 ++
> 4 files changed, 101 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/ABI/testing/configfs-vkms b/Documentation/ABI/testing/configfs-vkms
> index f750e616be54..4061ada5d88b 100644
> --- a/Documentation/ABI/testing/configfs-vkms
> +++ b/Documentation/ABI/testing/configfs-vkms
> @@ -48,6 +48,20 @@ Description:
> Value is a bitfield, where 0x1 = NO_DATA, 0x2 = SMPTE_170M_YCC,
> etc. See enum drm_colorspace for full list.
>
> +What: /sys/kernel/config/vkms/<device>/connectors/<connector>/edid_enabled
> +Date: Nov 2025
> +Contact: dri-devel@lists.freedesktop.org
> +Description:
> + Enable or disable EDID for this connector. Value:
> + 1 - enabled, 0 - disabled.
> +
> +What: /sys/kernel/config/vkms/<device>/connectors/<connector>/edid
> +Date: Nov 2025
> +Contact: dri-devel@lists.freedesktop.org
> +Description:
> + Content of the EDID for this connector. Ignored if
> + edid_enabled is not set.
> +
> What: /sys/kernel/config/vkms/<device>/connectors/<connector>/possible_encoders
> Date: Nov 2025
> Contact: dri-devel@lists.freedesktop.org
> diff --git a/Documentation/gpu/vkms.rst b/Documentation/gpu/vkms.rst
> index 1c4a8023374c..60367fd1bd65 100644
> --- a/Documentation/gpu/vkms.rst
> +++ b/Documentation/gpu/vkms.rst
> @@ -138,7 +138,7 @@ Last but not least, create one or more connectors::
>
> sudo mkdir /config/vkms/my-vkms/connectors/connector0
>
> -Connectors have 3 configurable attribute:
> +Connectors have 5 configurable attribute:
>
> - status: Connection status: 1 connected, 2 disconnected, 3 unknown (same values
> as those exposed by the "status" property of a connector)
> @@ -147,6 +147,9 @@ Connectors have 3 configurable attribute:
> If supported_colorspaces is not 0, the HDR_OUTPUT_METADATA will also be created.
> Value is a bitfield, 0x1 = NO_DATA, 0x2 = SMPTE_170M_YCC... see enum drm_colorspace
> for full list.
> +- edid_enabled: Enable or not EDID for this connector. Some connectors may not have an
> + EDID but just a list of modes, this attribute allows to disable EDID property.
> +- edid: Content of the EDID. Ignored if edid_enabled is not set
>
>
> To finish the configuration, link the different pipeline items::
> diff --git a/drivers/gpu/drm/vkms/vkms_configfs.c b/drivers/gpu/drm/vkms/vkms_configfs.c
> index 90bf6e6995ae..20f5150e8b24 100644
> --- a/drivers/gpu/drm/vkms/vkms_configfs.c
> +++ b/drivers/gpu/drm/vkms/vkms_configfs.c
> @@ -1271,14 +1271,94 @@ static ssize_t connector_supported_colorspaces_store(struct config_item *item,
> return count;
> }
>
> +static ssize_t connector_edid_enabled_show(struct config_item *item, char *page)
> +{
> + struct vkms_configfs_connector *connector;
> + bool enabled;
> +
> + connector = connector_item_to_vkms_configfs_connector(item);
> +
> + scoped_guard(mutex, &connector->dev->lock)
> + enabled = vkms_config_connector_get_edid_enabled(connector->config);
> +
> + return sprintf(page, "%d\n", enabled);
> +}
> +
> +static ssize_t connector_edid_enabled_store(struct config_item *item,
> + const char *page, size_t count)
> +{
> + struct vkms_configfs_connector *connector;
> + struct vkms_config_connector *connector_cfg;
> + bool enabled;
> +
> + connector = connector_item_to_vkms_configfs_connector(item);
> + connector_cfg = connector->config;
> +
> + if (kstrtobool(page, &enabled))
> + return -EINVAL;
> +
> + scoped_guard(mutex, &connector->dev->lock)
> + {
> + vkms_config_connector_set_edid_enabled(connector_cfg, enabled);
> +
> + if (connector->dev->enabled &&
> + vkms_config_connector_get_status(connector_cfg) !=
> + connector_status_disconnected)
> + vkms_trigger_connector_hotplug(connector->dev->config->dev);
> + }
> + return count;
> +}
> +
> +static ssize_t connector_edid_show(struct config_item *item, char *page)
> +{
> + struct vkms_configfs_connector *connector;
> +
> + connector = connector_item_to_vkms_configfs_connector(item);
> +
> + scoped_guard(mutex, &connector->dev->lock)
> + {

Sorry for the additional email. I forgot to mention that this brace should go
in the same line.

> + unsigned int len = 0;
> + const u8 *edid = vkms_config_connector_get_edid(connector->config, &len);
> +
> + memcpy(page, edid, min(len, PAGE_SIZE));
> + return min(len, PAGE_SIZE);
> + }
> +
> + return -EINVAL;
> +}
> +
> +static ssize_t connector_edid_store(struct config_item *item,
> + const char *page, size_t count)
> +{
> + struct vkms_configfs_connector *connector;
> +
> + connector = connector_item_to_vkms_configfs_connector(item);
> +
> + scoped_guard(mutex, &connector->dev->lock)
> + {
> + vkms_config_connector_set_edid(connector->config, page, count);
> +
> + if (connector->dev->enabled &&
> + vkms_config_connector_get_status(connector->config) !=
> + connector_status_disconnected)
> + vkms_trigger_connector_hotplug(connector->dev->config->dev);
> + }
> +
> + return count;
> +}
> +
> CONFIGFS_ATTR(connector_, status);
> CONFIGFS_ATTR(connector_, type);
> CONFIGFS_ATTR(connector_, supported_colorspaces);
> +CONFIGFS_ATTR(connector_, edid_enabled);
> +CONFIGFS_ATTR(connector_, edid);
>
> static struct configfs_attribute *connector_item_attrs[] = {
> &connector_attr_status,
> &connector_attr_type,
> &connector_attr_supported_colorspaces,
> + &connector_attr_edid_enabled,
> + &connector_attr_edid,
> NULL,
> };
>
> diff --git a/drivers/gpu/drm/vkms/vkms_connector.c b/drivers/gpu/drm/vkms/vkms_connector.c
> index c85d19013720..311858727175 100644
> --- a/drivers/gpu/drm/vkms/vkms_connector.c
> +++ b/drivers/gpu/drm/vkms/vkms_connector.c
> @@ -143,6 +143,9 @@ struct vkms_connector *vkms_connector_init(struct vkms_device *vkmsdev,
>
> drm_connector_helper_add(&connector->base, &vkms_conn_helper_funcs);
>
> + if (vkms_config_connector_get_edid_enabled(connector_cfg))
> + drm_connector_attach_edid_property(&connector->base);
> +
> return connector;
> }
>
>
> --
> 2.51.2
>